Hexafluorosilicic acid is the inorganic compound with the formula H2SiF6. It is a product of the production of hydrogen fluoride and the production of phosphate fertilizers. The majority of the hexafluorosilicic acid is used for the production of aluminium metal. Hexafluorosilicic acid is also commonly used for water fluoridation.

"Hydrogen fluoride is a hazardous air pollutant that is a highly corrosive and systemic poison that causes severe and sometimes delayed health effects due to deep tissue penetration. Absorption of substantial amounts of hydrogen fluoride by any route may be fatal.

One of the hydraulic fracturing companies used 67 222 gallons of two products containing hydrogen fluoride in 2008 and 2009."